Perspective drawing machine



Feb. 2, 1954 D. J. M QUAID, SR., ET AL 2,667,694 PERSPECTIVE DRAWING MACHINE Filed Dec. 27, 1949 12 Sheets-Sheet l INVENTORQ DAN J. McQUAID sR.

2 BY FREDR|CK W. RIEHL 1954 D. J. MCQUAID, SR., ET AL 2,667,694

PERSPECTIVE DRAWING MACHINE l2 Sheets-Sheet 2 Filed Dec. 27, 1949 INVENTOR. DAN J. MGQUAID SR. BY FREDRICK W. RIEHL Feb, 2, 1954 D, J. MCQUAID, sR., ET AL 2,667,694

PERSPECTIVE DRAWING MACHINE 12 Sheets-Sheet 3 Filed Dec. 27, 1949 INVENTOR. DAN J. MOQUAID SR. BY FREDRICK W. RIEHL Feb. 2, 1954 D. J. MCQUAID, sR., ET AL PERSPECTIVE DRAWING MACHINE l2 Sheets-Sheet 4 Filed Dec. 27, 1949 FIG. 8

Q R mm A MU Q O M J- N A D FREDRICK W. RIEHL Feb. 2, 1954 D. J. MCQUAID, sR., ET AL 2,667,694

PERSPECTIVE DRAWING MACHINE Filed Dec. 27, 1949 12 Sheets-Sheet 5 INVENTOR. DAN J. McQUAlD SR. FREDRIGK W. RIEHL Feb. 2, 1954 PERSPECTIVE DRAWING MACHINE Filed Dec. 27, 1949 12 Sheets-Sheet 6 INVENTOR. DAN J. McQUAlD SR. BY FREDRICK W. RIEHL zZa D. J. MOQUAID, sR., ET AL 2,667,694

Feb. 2, 1954 D, J, MCQUAID, sR.. ET AL 2,667,694

PERSPECTIVE DRAWING MACHINE 12 Sheets-Sheet 7 Filed Dec. 27, 1949 FIG.

INVENTOR. DAN J. McQUAID SR. FREDRICK w. RIEHL BY Feb. 2, 1954 D. J. MOQUAID, sR., ET AL 2,667,694 PERSPECTIVE DRAWING MACHINE l2 Sheets-Sheet 8 Filed Dec. 27, 1949 INVENTOR. DAN J. McQUAID SR. FRED'RICK W. RIEHL BYIV Feb. 2, 1954 D. J. M QUAID, SR, ET AL PERSPECTIVE DRAWING MACHINE Filed Dec. 27, 1949 12 Sheets$heet 9 FIG.

FIG.

INVENTOR. CAN J. MCQUAID SR. FREDRICK W. RIEHL D. J. M QUAID, sR., ET AL 2,667,69 PERSPECTIVE DRAWING MACHINE Feb. 2, 1954 Filed Dec. 27, 1949 12 Sheets-$heet l0 INVENTOR. DAN J. McQUAED SR. FREDRICK W. RIEHL 12 Sheets-Sheet ll Feb. 2, 1954 D. J. M QUAID, siin, E L PERSPECTIVE DRAWING MACHINE Filed Dec. 2'7, 1949 FIG. 2|

Feb. 2, 1954 J, McQUAlD, sR., ET AL 2,667,694

PERSPECTIVE DRAWING MACHINE Filed Dec. 27, 1949 12 Sheets-Sheet l2 INVENTOR. FIG. 24 DAN J. McQUAlD Sn. BY FREDRICK w. RIEHL Patented Feb. 2, 1954 2,667,694 PERSPECTIVE DRAWING MACHINE Daniel J. McQuaid, Sr., Riehl, Denver, 0010.;

Daniel J. McQuaid and Frederick William said Riehl assignor to said Application December 27, 1949, Serial No. 135,194

2 Claims. 1

This invention relates to various forms of drawing machines and tools especially adapted to facilitate the making of perspective drawings.

Previously many different types of drawing machines have been devised and quite a few of the prior types of drawing machines have been designed to facilitate the making of perspective drawings. Predominantly, however, the prior machines have been concerned with making perspective drawings from orthographic projections by means of linkage arrangements whereas only a few have been adaptable to the making of perspective drawings directly. Since the mechanism necessary to facilitate the making of perspective drawings from orthographic projections is relatively complex, machines of this general type have not received commercial adoption proportionate to the potential market for perspective drawing machines. It is believed that this failure to gain widespread usage has been the result of several important factors. In order to fully realize the sales advantages to be gained from wide scale usage, it is believed that a perspective drawing machine should be accurate, easy to operate, fast, portable, readily understandable, durable, economically constructed, easily adaptable to any commercial type drawing board, adaptable for making various types of perspective drawings, and useful in the drafting room as an aid to the performance of routine drafting duties as a replacement for various conventional draft ing tools. It is believed that all previous designs of perspective drawing machines have failed to capture the potential market for such machines by reason of failures to satisfy one or more of the foregoing requirements.

Realizing that a machine which satisfied all of the above requirements would be highly desirable, the present inventors have put forth concerted effort and research in developing the perspective drawing machines now presented. These machines are designed to satisfy the following objectives:

To provide a perspective drawing machine that is light in weight and economical of construction having relatively few parts.

To provide a perspective drawing machine having straight edge guide members disposed thereon to facilitate the drawing of lines radiating from a common axis which may be used as a vanishing point.

To provide a perspective drawing machine which incorporates mechanisms for moving such axis to desired positions on or off of the drawing surface of the machine thereby placing the vanishing points for the sired positions.

To provide a type of perspective drawing instrument which may be readily attached to conventional types of drawing boards.

To provide a perspective drawing machine in corporating means for automatically removing the guide edges used in drawing out of contact with the drawing board when not in use, together with further means in'specific forms of the invention for accurately repositioning the guide members in their exact previous position when the drawing operations are to be continued.

To provide a perspective drawing machine having at least one pivoted guide member, a straight edge of which is aligned with the pivot or axis of said guide member to facilitate the drawing of lines radiating from said pivot or axis.

To provide extension members for perspective drawing machines capable of supporting a guide member of the foregoing type in various selected positions around, above, over or on the drawing board.

Further objects and advantages of the present invention will be apparent from the appended description and drawings in which:

Fig. 1 is a dimetric drawing of a first embodiment of this invention;

Fig. 2 is a dimetric representation of a further embodiment of this invention;

Fig. 3 is a dimetric drawing showing modifications and improvements for the basic form shown in Fig. 1;

perspective drawing in de- Fig. 4 is an exploded view showing the compo--' nent parts of the pivot head utilized in the embodiment shown in Fig. 3;

Fig. 5 is a dimetric representation showing further modifications and attachments for the drawing machine of Fig. 3;

Fig. 6 is a dimetric drawing showing various modifications and improvements of the basic form shown in Fig. 2;

Fig. 7 is an exploded view of the component parts for the pivot head shown in Fig. 6;

Fig. 8 is an enlarged view showing additional features of the form shown in Fig. 6;

. Fig. 9 is a dimetric representation of modifications of the form shown in Fig. 6 showing one novel use of the present type of machine;

Fig. 10 is a dimetric drawing of a further modification of the basic form shown in Fig. 2;

Fig. 11 is a cross sectional elevation taken along the line H-l I of Fig. 10 showing structural features of this embodiment;

Fig. 12 is an exploded view of the pivot head construction for the embodiments shown in Fig.

Fig. 13 is an exploded view showing the structure of the slide guide and position return device shown in Fig. 10

Fig. 14 is an elevational View of a drawing machine made in accordance with this invention showing the drawing surface thereof in raised position and further showing the utility of this invention in aiding the drawing of perspective views in whichone vanishing pointis approximately five times further away from the central axis of the figure being drawn than the other vanishing point;

Fig. 16 is a dimetric representation of a basic form of this invention in which a single drawing edge may be selectively supported by pivots establishing the desired vanishing points;

Fig. 16 is a dimetric drawing showing a modification of the basic invention wherein the drawing edge is supported between spaced plates having'scale markings thereon; a

Fig. 1'7 is a planview showing one use of the basic equipment of this invention in which triangles are shown as being secured to the drawing edges to facilitate the drawing of systems of vertical or other lines and in which a separate locking device is provided for securing the drawing edges in adjusted position; 7 Fig. 18 is a plan view showing a further use of the basic devices of this invention in which the support head is moved up and down the edge of the drawing surface to facilitate the drawing of a system of parallel lines;

Fig. 19 is a plan view showing the use of the basic mechanisms of this invention to establish scalable perspective drawings through use or the third movable vanishing point;

Fig. 20 is a plan view showing the use or the basic drawing machine of this invention together with triangles of. special angularitv to establish desired systems of parallel lines;

Fig. 21 is a plan View showing the use of equipment provided in accordance with the principles of this invention to make one point perspective drawings;

Fig. 22 is a plan view showing the use of the basic mechanisms of this invention to make three point perspective drawings;

Fig. 23 is a dimetric representation showing the attachments necessary to convert the usual drawing board so as to make such drawing board useful in accordance with the principles of this invention; and

Fig. 24 is a plan view showing the various types of objects which may be drawn to the full size of the drawing surface with the aid of the perspective drawing machine of this invention.

Briefly stated the present invention provides in its simplest form a guide edge which is mounted for rotation about a bearing or pivot member in such manner that the guide edge is aligned with the axis of said pivot so that lines drawn with the aid of the edge will all radiate from the axis. Further provision is made for the selective placement of extension arms outwardly from the edges of the drawing board as supports for the pivot member and attached guide edge. In all embodiments the pivot member is slidably engaged with the extension arms to permit lateral adjustments in the placement of the pivot axis.

As refinements and improvements of the basic principle of this invention the inventor provides various attachments for positioning the pivot sistance between the rods axis and therefore the vanishing points of a perspective drawing above, on, or at positions removed from the drawing board. Further improvements provide for the automatic removal of the guide members from the face of the drawing board whenever desired, while cooperative mechanisms are provided to accurately reposition the guide members intheir previous positions. Through use of such novel arrangements and attachments the present inventors are able to facilitate the making of various regular types of drawings as well as distinctive perspective drawings.

Referring now to Fig. 1 it will be noted that the inventors provide edge members ll made of metal or other wear resistant materials for attachment to a conventional type ii. The edge members-ii are provided with a plurality of openings 53 in the outwardly disposed faces thereof. These openings l3 are threaded or otherwise adapted to engage and sup port extension rods it. At least one end ofthc extension rods id is adapted for cooperative reception in the openings it so that the rods will be securely held in positions extending laterally at 0 from the edge ii. In this first embodiment at least two rods M 'are placed in adjacent openings 53 so that the rods will extend in relatively close parallel relation. A bearing block it or pivot support member having holes ii therethrough is provided for sliding engagement with said rods l4; Preferably the holes H are of but slightly larger diameter than the diameter of the rods M so that the friction re- Hi and ii will be adequate to resist unintentional reciprocal movement of the block 15. A guide member iii having a straight edge is is mounted on the bearing block hi for pivotal movement about a pivot member 23 having an axis through the bearing block 15 at right angles to the fiat upper face thereof. The axis of the pivot is in line with the straight edge is so that all lines drawn with the aid of the edge is will in effect radiate from the said pivot axis. Though the details of structure are not shown in Fig. l, a locking device or nut 2| is provided for securing the guide member is in its adjusted position with respect to the pivot axis.

The detailed features of a locking device suitable for this particular application are shown in Fig. 4 where it will be noted that a hole 22 is drilled through the block it at right angles to the face of the block. A pivot pin 23 which is of a diameter which will fit snugly through the hole 22 is provided for engagement in the hole 22. In addition to the hole 22 the pivot pin 23 passes through fiat washers 24 and lock washer 26 which are separately arranged and adapted to provide for free rotational movement of the guide edge support member 2'? about the pivot 23 even though the nut 28 is snugly engaged with the pivot bolt 23 to complete a relatively rigid assembly. It should be understood, however, that with this particular arrangement it ispossible to engage the nut 28 securely on the pivot bolt 23 so that the guide support 2'! will be held in rigid position. For normal drawing operations, however, the tension on the nut 28 is adjusted so that the lock washer 26 will tend to offer only slight frictional resistance to the movement of the guide support 21. A modification of the form shown in Fig. 1 which fully utilizes the pivot and bearing block assembly described is shown in Fig. 3. In this figure the drawing board I2 is shown with a stand drawing board 29 providing adjustable, tilting support for the drawing board I2 through use of radius members 3| and lock nuts 32. Actually the support described is of conventional design; however, the drawing board I2 usually mounted on such support 29 has been modified through the provision of wear resistant edge members II equivalent to those shown in Fig. 1. Further, the openings I3 are provided in the edges I I for the identical purpose of providing support for the parallel extension rods I4. As before, the extension rods I4 slidably support the pivot support bearing blocks I6 about which guide members I8 are freely rotatable. In this figure the utility of providing a plurality of extension rod supports I3 is apparent inasmuch as it is here shown that the guide edges I8 may be supported for rotation about pivot axes at various positions around a drawing board I2. With the particular arrangement shown wherein the guide edges B are mounted for pivotal movement about pivot axes positioned beyond the lateral'sides of the drawing board I2, it will be apparent that two point perspective drawings may be readily executed by adjusting thepositioning of the guide edges I8 associated with the said pivots. In addition where the pivot axis is positioned along the top edge of the drawing board, it will be readily apparent that the making of one point perspective drawings will be greatly aided. If desired, all of the guide edges I 8 shown may be used at one time to execute three point perspective drawings.

An additional attachment for the drawing machine described is shown in Fig. 5. In this figure it should be noted that additional extension rods I4 are provided to support blocks 33 to which a cross member 34 is secured. The cross member is provided with a longitudinally extending slot 36 through which a pivot 3! may be extended. A guide edge I8a is preferably secured to the pivot 37 so that the forward edge I911 is in alignment with the axis of the pivot 31. A locking knob 38 is threadedly engaged to the pivot 3'! so that the guide edge I8a may be readily placed in desired positions and secured in such positions by tightening the lock nut 38 into engagement with the cross member 34.

A modification for the basic arrangement originally disclosed in Fig. 1 is shown in Fig. 2. In this figure it will be noted that the drawing board I2 is provided with wear resistant edge members II having holes I3 therein. As changes in the original structure, however, this particular embodiment utilizes only a single extension rod I4 as a support for each of the drawing guide edges. In order to fully utilize the advantages to be gained from the use of single support extension rods I4, the structure of the pivot support member is modified so that the bearing block 39 is provided with only a single through hole 4|. As before, the diameter of the hole II is just slightly greater than the diameter of the extension rods I4 so that the block 39 will fit snugly on the extension rod I4 for reciprocal motion therealong. A support plate 42 which is secured to the bearing block 39 by screws 43 (not shown in this figure) or other similar means and a pivot pin 44 extends downwardly through a protractor 46, the support plate 42 and into a bearing block 39. As inthe previous instance, the forward edge is?) of the guide member I8b is aligned with the axis of the pivot 44. One advantage inherent in this structural form is shown in Fig. 2 where it will be noted that the bearing block 39, support plate42 and guide member I8 may be rotated around the likewise placed over extension rod I4 to move the guide member I8 to an alternative position out of contact with the drawing board I2.

Refinements of the basic form shown in Fig. 2 are presented in Fig. 6 wherein it will benoted that the inventors provide a drafting table 41 as support for drawin board 48. Essentially the form shown in this figure is adapted for making perspective drawings on a relatively larger scale than the form shown in Fig. 2. Accordingly more rigid extension pieces 49 are provided to extend laterally from the table 41. To further assure rigidity of structure, extension support legs 5| having a base plate 52 are adjustably engaged with the extension pieces 49 by means of block clamps 53. Since the support legs 5I pass freely through the block clamps 53, the clamps may be adjusted to any desired height above the supporting floor by merely loosening and tight ening thumb screws 54. A cross rod 56 is provided which passes through bearing members 51 which are movable along the extension pieces 49' to adjusted positions as desired. Preferably the cross rod 56 is freely rotatable in the bearing blocks 5'! to facilitate the-removal of the guide members I from the face of the drawing board '38.

The further structural provide for the automatic removal of the guide members I 80 is shown in the exploded view of the pivot head as shown in Fig. 7., Here it will be noted that the inventors provide a pivot head support block 58 having an opening 59 transversely therethrough in which the cross rod 56 is engaged and secured by tightening of the set screw 6|. An upwardly disposed edge of the support block 58 is drilled and tapped to provide threaded holes 62 for the reception of support plate securing screws 43 and a central hole 63 for engaging and holding the pivot pin 44. A support plate 42 passes downwardly over the pivot pin 44 when it is in its engaged position in the opening 63, and fiat head screws 43 adapted for engagement in the holes 62 secure the support plate 42 in position above the support block 58. A balance rod 64 extends from the support plate and a counter-balancing weight 66 having an openin 61 transversely therethrough is adapted to slide along the length of the balance rod 64 cate radial positions of the guide member I 80 is secured to the support plate by a plurality of additional flat head screws 43. A central hole 12 through the protractor plate 69 permits the placement of the protractor 59 over the pivot pin 44. A spacer likewise placed over the pivot pin 44 to substantially cover the heads of the screws 43 while still exposing to View the scale markings H on the protractor plate 69. The guide member I80 having an opening I5 disposed centrally in a disk shaped portion ll of the guide member I80 is the pivot pin 44 for rotation thereabout. An additional spacer 13 having an opening 14 therein islikewise positioned over the pivot pin 44 as is a lock washer 18, a fiat washer is, adjusting nut BI and a lock nut 82.. In its final assembled relation the guide member is freely rotatable about the pivot pin 44 unless it becomes desirable to tighten the adjusting'nut 8| to hold the guide member I8c in fixed position. With this particular arrangement of parts, it will be readily observed that the counterbalance elements necessary to 73 havin a central opening 14 is' weight 66 may be positioned along the balance rod 64 so as to raise the guide members I80 out of contact with the drawing table 48 whenever the draftsman using the guide members releases his hold thereon. In the alternate position substantially as shown, the guide members I80 present no obstruction to'the view or further work on the drawingbeing executed.

In Fig. 8 this same arrangement of parts is shown in larger detail than in Fig. 6. Also in this figure it is shown that the inventors may, when they deem it necessary, attach a coil spring 83 to the cross rod 56 to dampen the normally fast movement of the guide members 180 to their alternate out of use position and to prevent the continued swinging of the guide members l8c after they have raised to the'out of use position.

In Fig. 9 the inventors show further modifications of the basic form shown in Fig. 2. In

this particular drawing the mechanism is shown as associated with conventional types ofshadow box equipment. Accordingly the stand 29 is shown as supporting a central shadow box 84 of relatively large dimension. This box is of conventional structure and design inasmuch as a sheet of plate glass 86 is supported above a light source (not shown) which is properly connected to a source of electric power by means of wires 81. As shown, a sheet of drawing paper 88 may be supported above the glass plate 86. Smaller shadow boxes 89 are placed along the lateral edges of the central box 84. These side boxes 89 are likewise provided with transparent plates 9| and suitable light source (not shown) therebeneath. These light sources are also connected with a source of electric power by means of wires 8?. The guide members E80 which are adapted to facilitate the drawing of lines converging at vanishing points on either side of the paper 88 are supported in their adjusted positions on extension rods M which are secured in holes l3 provided in the sides of the shadow boxes 89. As in Fig. 6, support legs are provided to give greater strength and rigidity to the extension rods Id. The structure for the guide member supports is substantially the same as that shown in Figs. 6, 7 and 8 except that a segment protractor 92 of larger dimension than the protractor 69 is provided. However a modified type of support for a center guide member I80 is shown. In this form a strap member 93 is provided which has a plurality of holes 94 therein. The strap member is secured to a hinged block 96 which is likewise secured to one of the extension rods l4 extending upwardly from the top edge of the shadow box 84. It is intended that-a segment protractor 91 may be selectively positioned and secured to the strap member 93 at any of the successive holes 94 inasmuch as the pivot pin 98 for this form of mount is removable. At the same time that the protractor is moved the guide member 180 will likewise be moved to rotate about the pivot pin 98 in its newly adjusted position. Since the block 56 is hinged and since a balance rod 99 and baiance weight I I'll are provided it will be apparent that whenever the guide member l8c is released by the draftsman the guide member, the protractor and the strap 93 will all be ele vated to an out of use position. Accordingly it is likewise possible with this design to completely clear obstructions from the drawing surface of the paper 88.

v Anovel use of this drawing machine together with the shadow'box equipment shown is indi cated on Fig. 9. This use accomplishes the re production of perspective drawings or photographs in enlarged scale. The operation is carried out in the following manner:

Two drawings of reduced scale or photographs Hi2 are placed above the transparent plates ,9! of the opposite shadow boxes 89. The pivot support heads of the drawing machine are then adjustably positioned so that the axis of the pivot corresponds to the apparent vanishing point for the photograph. The guide members are then brought down into posi on so that the forward drawing edge i9c of the guide members is aligned with principal lines in the photograph. A line is then drawn on the face of the sheet of paper 8.3 using the edge of the guide member to determine the direction and position of the line. The opposite pivot head support member is then adjusted so that the axis of the pivot will correspond to a second apparent vanishing point forthe photograph mounted above the oppositeshadow box 89. placed in position so along the point of termination in the photograph )2 of the line previously extended by the first guide member. This placement will determine the extent or length of the line being drawn on the paper 38. In similar manner further lines in the photograph are extended and positioned until all Of the detailed features of the photographs are duplicated in enlarged scale on the face of the paper 38, the product being a perspective view line drawing.

Figs. 10, ll, 12 and 13 show other modifications and improvements of the basic disclosure in Fig. :2. Here extension rods is engaged in holes is in edge pieces I l on the board 12 provide support for pivot head structures substantially as shown in Fig. 7, the detailed parts of which are shown in Fig. 12. As shown in Fig. 12, the applicants here provide a bearing block H13 having a transverse opening H34 therethrough of diameter slightly greater thanthe diameter of the extension rod M so that the bearing block its will be freely movable along the extension rod. A further hole IE6 is provided through the upper face of the bearing block 83 for the reception of the end of a pivot bolt I81. A spacer sea, a support blade H39, a segment protractor Hi, washers H2 and a guide head support i !3 are all likewise provided with holes through which the pivot bolt Hi1 will extend. When in assembled relation the guide head H3 is rotatable about the pivot bolt Hi1 while the protractor and support plate remain stationary.

A guide edge n4 is provided having openings H6 therein for cooperative positioning with the openings H1 and the guide head support H3. Screws or other means are used to secure the guide edge ms to the guide edge H3 when these holes are in aligned position. Since the principal feature of the present modification is the provision of a second guide arm which is rotatable about the pivot which is slidable longitudinally of the guide edge 1M, rails H5 are p1'0 vided which are adapted to be secured on the guide edge He by means of screws H9 or the like. Preferably the rails H8 are of different size so that the rails l I80. resting adjacent to the guide edge iii are of lesser width than the rails 8b mounted above the rails 3a. This size relation provides a channel 25 between the rails in which a slide member 122 may be engaged for reciprocal motion along the length of the guide edge H4.

The guide member I is then that the edge iec passes- As shown in Fig. 11, the slide I22 reciprocates between the rails I I Bet whereas a spacer-member I23 moves reciprocally between the rails IIBb. It will be apparent that with this arrangement the slide I22 cannot be removed from its position between the rails H8. Slide I22 is provided with a central opening I24 adapted for the reception of one end of a pivot bolt I26. Further the slide I22, spacer I23 and a disk support plate I2? are all provided with openings through which screws I28 or other fastening devices may be passed to hold the said members in permanent arrangement. In their assembled relation a further plate I23 is positioned above the support plate I 27 tractor 29 is positioned above the plate I28. Plate I 28 is provided with an opening I 3! through which the pivot pin I26 passes, and a second opening I32 adapted for the reception of the end I33 of a stop pin I34. I23 is likewise provided with a central opening I36 and an opening I37 into which the stop pin may extend. A guide arm I38 is provided having an opening I33 through which the pivot pin I26 extends, and a second opening I 4| adapted to receive and hold the stop pin I34.

When in the assembled relation as shown in Fig. 10, the pivot bolt I26 may be loosened so that the guide arm I38, protractor I29, and plate I28 will rotate freely. With the pin in its engaged position the angularity of the guide arm I38 is adjusted until it assumes a desired position. The pivot bolt is then tightened to secure the plate I23 in its adjusted position. Thereafter the stop pin I34 may be lifted so that the end I 33 comes out of contact with the hole I32 in plate I28. Since the pin I34 is out of engagement with the hole I32 the guide arm I38 may be freely rotated to other positions. If desired the guide arm may be put into a position along the guide edge H4 and the mechanism may be used in the manners previously described. Whenever it is desired to re-execute additional lines that were drawn with the guide arm in its adjusted position, the guide arm may be rotated to that position at which time the pin I34 will again move into engagement with the hole I32 and plate I28 to secure the guide arm I38 accurately in its original position. Since the guide arm i38 will be used principally for making vertical lines or other sets of parallel lines, it is essential that means be provided for securing the guide arm H4 in accurate predetermined positions. This is possible in several different ways with the structure shown. First, bushings I42 as shown in Fig. 12 may be secured on the extension rod I4 by tightening set screws I43 mounted on the bushings I42. Locking these bushings I42 in place will prevent translational movement of the block I 83 along the extension rod I4 while pivotal movement about the rod I4 is still possible. While the angular position of the guide member I I4 can be fixed by tightening the nut I44 on the pivot bolt I87, the excessive tightening necessary is usually not desirable. Accordingly the inventors provide a clamp I46 having upper and lower spring members I 41 which may be slipped over the edge II of the body I2 and over the face of the guide member I I4 to securely hold the guide member in a fixed position.

While this one particular arrangement is shown it should be obvious that other means such as C clamps or the like could be provided and further that a pin locking device similar to Pin I34 and a pro- .715

The protractorqgo .of perspective drawings, these could be positioned to hold the guide head support I I3 in fixed position with respect to the protractor and plate III and H33 respectively. Whatever the means used for securing the guide member H4 in position may be, it is obvious that reciprocal motion of the slide I22 between the guides H3 will move the guide edge I38 through a plurality of parallel positions.

It will be obvious that the various forms of the present invcntionare adaptable for many different utilitarian purposes. 'Likewise it will be noted that while the various mechanisms are specifically designed for aiding the production same tools are adaptable for the accomplishment of various routine drafting operations.

Among the special jobs which will be facilitated by this drawing machine are the making of perspective drawings in which the position of either one, two or three vanishing points may be adjusted to positions above, on or removed from the drawing surface. Further when the drawing surface is arranged in raised position the mechanisms of this invention will facilitate the making of accurate layouts and guide lines for paintings, etchings, murals or various types of commercial art design. Another very important use for this machine is in making accurate lithographers line drawings for color separation work and other printing mats. Likewise this machine can be used to make exploded drawings of machine parts from smaller drawings or photographs as well as for retouching work in photographs.

A special feature of this machine is embodied '11 its inherent usefulness to make perspective drawings that are actually diminish in the direction of the vanishing point. These scalable drawings can be made the entire size of the it is possible to accurately It will be apparent that adaptable to various other modifications and be a part of this invention.

What is claimed is:

the principal lines of objectives placed and viewed above said shadow box.

2. A perspective drawing machine, comprising a rectangular frame, including a flat top surface centrally of the frame for the support of material to be drawn on, and an adjoining surface for the support of copy to be drawn, a plurailty of openings at intervals along the length of the frame exteriorly of said drawing and copy-supporting surfaces, two bodies adapted for attachment to opposite sides of said frame and a third body adapted for attachment to the top edge of said frame, each including at least one rod for selective penetration of said openings, and guide means in pivotal connection with each said body having a straight edge in radial alinement with the pivotal axis and extending over the drawing surface, and said side-mounted guide means also extending over the copy surface so as to permit. perspective enlargement of the copy lines on said drawing surface.

DANIEL J. McQUAlD, SR. FREDERICK WILLIAM RIEHL.

12 References Cited in the file of this patent UNITED STATES PATENTS Number Number Name Date Putnam June 26, 1883 Hickok June 24, 1890 Bing July 18, 1905 Webster Jan. 16, 1923 De Postels Jan. 24, 1928 Shattaw Mar. 3, 1931 Langsner May 20, 1941 FOREIGN PATENTS Country Date Great Britain Mar. 31, 1939 Great Britain Oct. 1'1, 1940 Great Britain Aug. 26, 1947 

